1. Field of the Invention
The present invention relates to an automatic document feeder. Further, the present invention relates to an image scanning device including the automatic document feeder. Furthermore, the present invention relates to a method for feeding an original document.
2. Description of the Related Art
In a conventional automatic document feeder, a plurality of feed roller sets are arranged along a feeding path, and the plurality of the feed roller sets feed an original document (See, for example, Japanese Unexamined Patent Application Publication No. 2010-269934). Specifically, a one side feeding path dedicated for scanning one side of an original document and a two side feeding path dedicated for scanning both sides of an original document are provided. The plurality of the feed roller sets are arranged so that an original document can be fed along such feeding paths.
In the conventional automatic document feeder, the plurality of the feed roller sets feed an original document along the dedicated one side feeding path and the dedicated two side feeding path to scan the content of the original document. However, in such a conventional automatic document feeder, the plurality of the feed roller sets are prepared for the dedicated one side feeding path and the dedicated two side feeding path, respectively. Consequentially, there have existed a feed roller set(s) that is not used to scan one side of an original document but used only to scan both sides of an original document. For example, feed roller sets 42 and 43 (of the above-referenced publication) correspond to such a feed roller set. The existence of the feed roller set that is used only to scan both sides of an original document has forced the conventional automatic document feeder to include more feed roller sets than an automatic document feeder configured otherwise. Various unsuccessful efforts have been made to reduce the number of feed roller sets.